Adaptive confirmation of treatable arrhythmia in implantable cardiac stimulus devices
First Claim
1. A method of operation in an implantable cardiac stimulus device (ICSD) comprising a housing that contains a battery power source and operational circuitry that operates by analyzing cardiac signals from implanted electrode(s) in order to determine whether a treatable arrhythmia is detected, the method comprising:
- the ICSD making an initial determination that a treatable cardiac arrhythmia is occurring;
the ICSD preparing to deliver therapy in response to the initial determination and, while preparing to deliver therapy, observing whether indications of benign cardiac rhythm are detected;
when the ICSD is prepared to deliver therapy, applying Confirmation criteria to confirm the treatable cardiac arrhythmia is ongoing, the Confirmation criteria comprising a Therapy threshold and the Confirmation criteria is applied by;
counting intervals between events detected from sensed cardiac signals that are shorter than a short interval threshold to generate a Short Interval Count (SIC); and
comparing SIC to the Therapy threshold; and
if the Confirmation criteria are met, delivering therapy from the ICSD;
wherein the method comprises the ICSD changing the Confirmation criteria in response to identification of one or more of the indications of benign cardiac rhythm while the ICSD is preparing to deliver therapy by increasing the Therapy threshold to require a larger SIC value;
further wherein the Confirmation criteria are actively updated and re-applied until either therapy is delivered or the ICSD determines that therapy is not needed;
further wherein;
the ICSD uses an event detection method in which events are detected from sensed cardiac signals, and intervals between the detected events are used to estimate cardiac rate for use in the initial determination that a treatable cardiac arrhythmia is occurring.
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Abstract
Methods and devices for adjusting therapy delivery decisions in an implantable cardiac stimulus device by observing cardiac activity following an initial identification of a treatable condition. In some examples, cardiac activity that appears benign is quantified and a therapy confirmation threshold is adjusted according to how much apparently benign cardiac activity is seen after an initial identification of a treatable condition. In other examples, a new threshold is applied following the initial identification of treatable condition, removing historical data preceding the initial identification from subsequent therapy delivery decisions.
228 Citations
25 Claims
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1. A method of operation in an implantable cardiac stimulus device (ICSD) comprising a housing that contains a battery power source and operational circuitry that operates by analyzing cardiac signals from implanted electrode(s) in order to determine whether a treatable arrhythmia is detected, the method comprising:
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the ICSD making an initial determination that a treatable cardiac arrhythmia is occurring; the ICSD preparing to deliver therapy in response to the initial determination and, while preparing to deliver therapy, observing whether indications of benign cardiac rhythm are detected; when the ICSD is prepared to deliver therapy, applying Confirmation criteria to confirm the treatable cardiac arrhythmia is ongoing, the Confirmation criteria comprising a Therapy threshold and the Confirmation criteria is applied by; counting intervals between events detected from sensed cardiac signals that are shorter than a short interval threshold to generate a Short Interval Count (SIC); and comparing SIC to the Therapy threshold; and if the Confirmation criteria are met, delivering therapy from the ICSD; wherein the method comprises the ICSD changing the Confirmation criteria in response to identification of one or more of the indications of benign cardiac rhythm while the ICSD is preparing to deliver therapy by increasing the Therapy threshold to require a larger SIC value; further wherein the Confirmation criteria are actively updated and re-applied until either therapy is delivered or the ICSD determines that therapy is not needed;
further wherein;the ICSD uses an event detection method in which events are detected from sensed cardiac signals, and intervals between the detected events are used to estimate cardiac rate for use in the initial determination that a treatable cardiac arrhythmia is occurring. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An implantable cardiac stimulus device (ICSD) comprising a housing that contains a battery power source and operational circuitry that operates by analyzing cardiac signal data from implanted electrodes in order to determine whether a treatable arrhythmia is detected, ICSD configured to perform a method of verifying therapy delivery comprising:
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the ICSD making an initial determination that a treatable cardiac arrhythmia is occurring; after making an initial determination that a treatable cardiac arrhythmia is occurring, the ICSD preparing to deliver therapy; while the ICSD is preparing to deliver therapy, observing whether indications of benign cardiac rhythm are detected; when the ICSD is prepared to deliver therapy, the ICSD applying Confirmation criteria to ensure the treatable cardiac arrhythmia is ongoing, the Confirmation criteria comprising a Therapy threshold and the Confirmation criteria is applied by; counting intervals between events detected from sensed cardiac signals that are shorter than a short interval threshold to generate a Short Interval Count (SIC); and comparing SIC to the Therapy threshold; and if the Confirmation criteria are met, the ICSD delivering therapy; wherein the method comprises the ICSD changing the Confirmation criteria in response to identification of one or more indications of a benign cardiac rhythm while the ICSD is preparing to deliver therapy by increasing the Therapy threshold to require a larger SIC value; further wherein the Confirmation criteria are actively updated and re-applied until either therapy is delivered or the ICSD determines that therapy is not needed;
further wherein;the operational circuitry is configured to use an event detection method in which cardiac events are detected from the sensed cardiac signals, and intervals between the detected cardiac events are used by the controller to estimate cardiac rate for use in the initial determination that a treatable cardiac arrhythmia is occurring. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. An implantable cardiac stimulus device (ICSD) that operates by analyzing cardiac signal data from implanted electrodes in order to determine whether a treatable arrhythmia needs therapy by:
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detecting cardiac events using the implanted electrodes; establishing an X/Y Counter with X indicating a number of Treatable detected cardiac arrhythmia events out of a set of Y detected cardiac events; and determining whether the X/Y Counter meets at least a Therapy threshold condition and, if so, the ICSD determining that a treatable arrhythmia needs therapy and beginning to prepare for therapy delivery, wherein the Therapy threshold condition calls for X/Y to yield 18 out of 24 detected cardiac events as Treatable detected cardiac arrhythmia events; wherein the ICSD is also configured to perform a method of verifying therapy delivery when the ICSD begins to prepare for therapy delivery, the method of verifying therapy delivery comprising; resetting the X/Y counter such that X is zero; detecting cardiac events and refilling the X/Y counter while the ICSD prepares to deliver therapy; determining that the ICSD is ready to deliver therapy; once the ICSD is ready to deliver therapy, if the X/Y counter exceeds a Confirmation threshold condition, delivering therapy;
or, if not, waiting for additional detected cardiac events, in which the Confirmation threshold condition calls for X/Y to yield 12/16 detected cardiac events as Treatable detected cardiac arrhythmia events. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. An implantable cardiac stimulus device (ICSD) comprising a canister housing operational circuitry for the ICSD, the operational circuitry including a defibrillation capacitor for storing defibrillation energy and a charging circuit for charging the defibrillation capacitor to a therapeutic energy level, the canister including at least one electrode thereon, and a lead electrode coupled to the canister and carrying electrodes coupled to the operational circuitry, the operational circuitry being configured to perform a method comprising:
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capturing cardiac signals from the electrodes; determining that a tachyarrhythmia or fibrillation is occurring and needs therapy; activating the charging circuit to charge the defibrillation capacitor; detecting cardiac events after the charging circuit is activated and keeping a long interval count by; a) establishing an initial value for the long interval count when the charging circuit is activated, and b) incrementing the long interval count when a long interval between two detected cardiac events occurs, or c) decrementing the long interval count when a short interval between two detected cardiac events occurs, the decrementing step being limited by the initial value; determining whether charging is complete, and, if so, determining whether a Confirmation condition is met, the Confirmation condition requiring a series of detected cardiac events to indicate therapy delivery, wherein the series of detected cardiac events has a length defined by the long interval count, and if so, delivering therapy to the patient.
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Specification